Out of Breath

I don't know what has happened to me. In high school I was on the cross country team and used to run rediculious amounts of miles every day. Today I walked up three flights of stairs and I found myself out of breath. When did this happen? Slowly and slowly I get more and more out of shape. I have a jam packed lifestyle, so I really dont have time to excersize and eat healthy anymore. I was never a big fan of fast food, but I am a fan of having food fast. There are not many alternatives. I just hope I can find time to slow down and start eating right.